The prevalence of hypertension in older Mexican-Americans in the southwest United States has increased slightly in the last decade, according to a new study.

The results showed the hypertension prevalence rate was 73 percent in 1993-1994, compared with 78.4 percent in 2004-2005. The increase in hypertension prevalence was significant for subjects 75 to 79 years, for U.S.-born subjects, for subjects with diabetes and for the obese, the researchers said.

The rise is likely due, in part, to increases in diabetes and obesity, researchers from the University of Texas Medical Branch at Galveston said in a statement.

"We always expect that things are improving, right?" said study researcher Kyriakos Markides, a professor of aging studies at the university. "But now we're finding that, in the more recent study participants, they're more disabled, have more diabetes, have slightly more obesity and slightly more hypertension."

Although hypertension, or high blood pressure, is one of the most common diseases in the United States, affecting more than 72 million Americans, it is one of the most manageable risk factors for cardiovascular disease, the researchers said.

The researchers studied 3,952 older Mexican-Americans living in Texas, New Mexico, Colorado, Arizona and California. They evaluated 3,050 men and women, ages 65 and older, in 1993-1994, and an additional 902 men and women, ages 75 and older, in 2004-2005. Researchers interviewed the study subjects and took health measurements every two to three years.

Study participants were considered hypertensive if they had been told by a physician that they had hypertension, if they had an average systolic blood pressure of 140 mm Hg or higher or an average diastolic blood pressure of 90 mm Hg or higher, or if they were taking antihypertensive medications.

While overall hypertension awareness was significantly higher in 2004-2005 than in 1993-1994 (82.6 percent vs. 63 percent, respectively), diabetic and obese subjects were more likely to be hypertensive in 2004-2005 than in 1993-1994.

There's good news and bad news, Markides said. "The bad news is the prevalence of hypertension went up not a huge increase, but up nonetheless due in part to obesity and diabetes. The good news is that the hypertension is better controlled because of increased awareness and better management."

Hispanics living in the United States are expected to number 120 million by 2050, the researcher said.

"This is a long-living population with increasing rates of disability, diabetes and chronic disease," said Markides.

"More effort should be targeted to reverse trends of both obesity and diabetes as potential causes of increases in hypertension," wrote Markides and his collaborators. "Further investigations should be directed toward providing clear guidelines and goals for hypertension treatment and control in the very old to improve hypertension outcomes in this population."

The study is published in the January issue of the Annals of Epidemiology and was funded by the National Institute on Aging.